1. Field of the Invention
This invention relates to fire extinguishing methods utilizing the completely fluorinated C.sub.2, C.sub.3 and C.sub.4 saturated molecules, C.sub.2 F.sub.6, C.sub.3 F.sub.8 and C.sub.4 F.sub.10.
2. Description of the Prior Art
The use of certain bromine, chlorine and iodine-containing halogenated chemical agents for the extinguishment of fires is common. These agents are in general thought to be effective due to their interference with the normal chain reactions responsible for flame propagation. It is taught in the art that the effectiveness of the halogens is in the order Br&gt;Cl&gt;F, for example, C. L. Ford, in Halogenated Fire Suppressants, R. G. Gann, ed., ACS Symposium Series 16. This order of effectiveness is also taught in da Cruz, Bull. Soc. Chim. Belg.. 97, 1011 (1988), which reports the inhibiting properties of a series of methanes is in the order CF.sub.3 Br&gt;CFCl.sub.3 &gt;CF.sub.2 Cl.sub.2 &gt;CF.sub.3 Cl&gt;CF.sub.3 H&gt;CF.sub.4. It is taught that compounds containing the halogens Cl, Br and I act by interferring with free radical or ionic species in the flame and that the effectiveness of these halogens is in the order I&gt;Br&gt;Cl&gt;F.
In contrast, perfluorocarbons (i.e., compounds containing only C and F atoms), have not heretofore been employed for the extinguishment of fires, since they have been regarded as not displaying any chemical action in the suppression of combustion. Thus, it is generally taught that to be effective as a fire extinguishing agent, a compound must contain Cl, Br or I.
The use of iodine-containing compounds as fire extinguishing agents has been avoided primarily due to the expense of their manufacture or due to toxicity considerations. The three fire extinguishing agents presently in common use are all bromine-containing compounds, bromotrifluoromethane (CF.sub.3 Br), bromochlorodifluoromethane (CF.sub.2 BrCl), and dibromotetrafluoroethane (BrCF.sub.2 CF.sub.2 Br). Although not employed commercially, certain chlorine-containing compounds are also know to be effective extinguishing agents, for example chloropentafluoroethane (CF.sub.3 CF.sub.2 Cl) as described in U.S. Pat. No. 3,844,354 to Larsen.
Although the above named bromine or chlorine-containing agents are effective in extinguishing fires, agents containing bromine or chlorine are asserted by some to be capable of the destruction of the earth's protective ozone layer.
It is therefore an object of this invention to provide a method for extinguishing fires that extinguishes fires as rapidly and effectively as the presently employed agents, and is environmentally safe with respect to ozone depletion.